Field of the Art
The present invention relates to a process for granulating carbonaceous powders. Particularly, it relates to a process for granulating by spray-drying a carbonaceous pulverulent body which contains a self-sintering carbonaceous powder and, if desired, at least one member selected from the group consisting of graphite-rich carbons, carbon-rich carbons, metals and inorganic compounds, and which is dispersed in water in the presence of a binding agent and a wetting agent into a heated air which can, if desired, contain superheated steam.
More particularly, the present invention relates to a process for granulation in which a carbonaceous pulverulent body comprising (1) a self-sintering carbonaceous powder which is a powder of a pitch selected from the group consisting of coal-tar pitches, petroleum pitches, degraded naphtha tar pitches, mesophase-containing or heat-treated pitches and other modified pitches and/or a complex powder selected from powders of the group consisting of graphite-rich carbons, carbon-rich carbons, metals and inorganic compounds the surfaces of which have been substantially covered with the pitch referred to just above and (2), if desired, at least one powder selected from powders of the group consisting of graphite-rich carbons, carbon-rich carbons, metals and inorganic compounds is dispersed in water in the presence of a binding agent and a wetting agent and the slurry is then subjected to granulation by spray-drying it in a heated air which can contain superheated steam. The granular products according to the present invention are advantageous in that, when the granular product is pressed in a mold into a molded product of a complicated shape and the molded product is further carbonized and/or graphitized to obtain a carbonaceous product of a precision form, the granular products of the present invention are capable of being filled into such a variety of molds as having a narrow or complicated mold cavity, without unevenness in the filling compactness thanks to the fact that the initially formed compacted product is easily disintegrated into a final form.
The granular pulverulent body of the present invention not only brings about the change in the process in that a large quantity continuous molding will be made possible in the field of small size precision molding by means of a mold with use of a pressing machine but also produces compacted products of an increased denseness thanks to an improved flow characteristic in the production of various forms by means of hydrostatic pressing (CIP), high temperature isotropic pressing (HIP) or the like, endowed with another advantage that a granulation adjuvant, i.e. a binding agent and a wetting agent, will not impair the strength of a sintered product.
The pulverulent body of the present invention is a material suitable for a process for producing small size carbonaceous molded products having a dimension accuracy not by the conventional cut processing of a carbon-rich and/or graphite-rich block form but by cold press molding in a mold and then carbonizing and/or graphitizing the form.